1. Field of the Invention
This invention relates to an effective adsorption refrigeration system which takes advantage of adsorption and desorption actions of a refrigerant by a solid adsorbent to perform refrigerating operation or heat pump operation. More particularly, it relates to an adsorption refrigeration system which is operated by transferring a heat transfer medium for heating an adsorbent, etc. remained in a first adsorption column immediately before shifting from a desorption stage to an adsorption stage, to a second adsorption column immediately before it comes into a desorption stage thereby to preheat the adsorbent, thus availing itself of the residual heat and enhancing a system efficiency.
2. Statement of Related Art
Adsorption refrigerators which take advantage of adsorption and desorption actions of a refrigerant by a solid adsorbent to generate cold or heat or to perform heat pump operation are known in the art and advantageous in that low-grade heat sources (e.g. warm water in the neighborhood of 85.degree. C.) such as warm water obtained from solar collectors etc., or waste heat made available from works can be harnessed effectively and that each of them is made up of a smaller number of mobile components such as pumps, being more economical in respect of apparatus cost, and operational noise is smaller, as compared with compressor type refrigerators.
In a known adsorption refrigerator of this type, two sets of adsorption columns housing therein a solid adsorbent such as silica gel, zeolite, activated charcoal, activated alumina, etc. are installed in parallel and are systematized so that a heat transfer medium for heating the adsorbent and cooling water may be supplied alternately to both adsorption columns to repeat adsorption and desorption stages whereby refrigerating power output can be continuously obtained. For example, U.S. Pat. No. 4,610,148 discloses a heat pump system under this category.
With such an adsorption refrigerating system, however, when adsorption and desorption stages are changed over, warm water remaining within the one adsorption column, which has just finished a desorption stage, is forced out by cooling water for shifting the column to an adsorption stage and discarded to a cooling water generator such as a cooling tower, for which a packing material fragile to heat, e.g. rigid polyvinyl chloride is used. As a consequence, the packing material exposed to the warm water is degraded early and whole amount of the warm water in the adsorption column used for desorption is discarded without heat recovery, which causes significant heat loss and results in reduction of the system efficiency by that loss.
Further, adsorption refrigerators of a kind that the evaporator is full of a working fluid in which heat transfer tubes are wholly immersed are also known and disclosed in, for example, Japanese patent publication A1 60-11072 (1985), Japanese patent publication No. A1 57-80158 (1982), etc. In this case, however, pressure of the working fluid always acts upon the exterior faces of the heat transfer tubes, and consequently, ebullition on the surfaces is difficult to occur and sufficient system efficiency could not be obtained.